mole

Metric (SI) unit of amount (not mass or weight) of a substance. One mole is defined as the amount of substance containing as many elementary entities (atoms, molecules, ions, electrons, radicals, etc.) as there are atoms in 12 grams of carbon-12 (6.023 x 1023). The mass of one mole of a substance equals its relative molecular mass expressed in grams. Also spelled as mol. Also called gram-molecular weight.